1. Department of Pediatrics; Instituto Nacional de Cancerologia; Bogota Colombia
2. Division of Hematology/Oncology; Boston Children's Hospital; Harvard Medical School; Boston Massachusetts
3. Department of Surgery; Instituto Nacional de Cancerologia; Bogota Colombia
4. Department of Pediatric Oncology; Dana-Farber Cancer Institute; Harvard Medical School; Boston Massachusetts
5. Department of Biostatistics and Computational Biology; Dana-Farber Cancer Institute; Harvard Medical School; Boston Massachusetts